South Branch intelligencer. [volume] (Romney, Va. [W. Va.]) 1830-1896, 1887-09-09
GATHERING GOLD.
An Explanation Of the Mining
Methods in Colorado.
Machinery Used In Separating
the Metal From the Ore.

a. Dreckenriuge, COL, the other day
says correspondent in the Globe Demo-
crat, ! saw the Jumbo stamp-mill, and
there got fair insight into the meth cd
OF getting the gold out of W hat is called
free milling ore. The stuff that comes
from the mine is first put through a
crusher, which breaks it up fine, and the
product is then run through rollers
which pulverizes it, though, perhaps.
coarsely. From the rollers it falls to
the lower floor, upon which the mortars
are located. At the Jumbo mill the dirt
is fed to the stamps by hand; in other
mills 1t falls through chutes which work
automatically, and never feed more than
Is necessary at time The stamps are
arranged in batteries OF five stamps each
They work up and down in oak case
ments, and their motions are regulated
by cams on shaft geared to the motive
machinery. The stamps weigh from $50
to 300 pounds, according to the charac-
ter OF the ore treated. Water flows into
the mortars and out of them down
tables to the waste fumes which carry
the refuse away. Stamps in this
country run as slow as thirty drops
a minute, and seldom over sixty;
In California they drop seventy to 100
times minute. They cost from $3.50
Tor five-stamp prospecting mill to $50
ooO for 100-stamp mill Tho dirt be-
ing led into the mortars is pounded and
pounded by the stamps; the silica,
porphyry and other refuse is carried off
by the water, but the gold is caught by
two copper plates coated with quicksil-
yer that line the sides of the mortar: anv
OF the precious metal that escapes from
the mortar may be caught on the AXIS
feet copper plates that are quicksilver
coated and lie on the table over which
the refuse is carried. Some of the gold
gets away, of course, but the Jumbo
saves as much as 80 per cent of its gold,
and Mcfarland is now building mills
which he claims will save 90 per cent of
essayed value of ore.
Concentrations are used where the ore
is too low grade to pay for smelling in its
crude state. BY concentrating a $40 or
$12 ore may be handled so that the nh
product which will represent six or
seven tons in ore, may be worth $40 to
$50 per ton. The scheme is very sim
pie. The crushed and rolled ore are fed
through shutes to revolving screens,
ranging in size from three fourths inch
openings to one eighth. Each of these
screens has trough and chute which
feads jig box. The jig boxes work on
an eccentric and keep up spasm-like
motion. There is a screen in each about
SIX inches from the top, and this screen
Is covered with lead or other heavy ore
material, which prevents the silica
porphyry and other light stuff from GO
ing through. The motion shakes the
metal to the bottom of the boxes, where
It remains until valves in the bottom are
opened and the concentrates arc re-
moved This machine, like all the
others called by different names, and
known as triumphs, frue vanners, bud
dies, bump plates, etc, is an application
of the well known law of specific gravi-
ty; the heaviest material falls to the
bottom in all these machines, and the
light stuff goes dancing away on the
water. The bump plate which is
claimed to be a new invention by Peter
Mcfarland, is large steel plate set at
an incline of few degrees; the orc is
fed to the lower part of the place from a
water trough and as the high end
bumps it carries forward and up over
the top of the plate the heavy concen-
trates.